class Solution
{
public:
    int climbStairs(int n)
    {
        vector<int> dp(n + 1);

        dp[0] = dp[1] = 1;
        for (int i = 2; i <= n; i++)
        {
            dp[i] = dp[i - 1] + dp[i - 2];
        }
        return dp[n];
    }
};